1. Field of the Invention
The present invention relates in general to oil distribution gear pumps for oil distributors used in refueling stations and, more particularly, to an oil distribution gear pump with an integrated air separator for separating air from oil bubbles.
2. Description of the Prior Art
Conventionally, oil distributors used in refueling stations include oil distribution gear pumps at their lower inner parts, respectively, for sucking up oil, such as gasoline and volatile oil, out of underground oil reservoirs and distributing the oil to an object to be refueled, such as automobiles and similar vehicles. Here, as well noted to those skilled in the art, a plurality of oil bubbles have been naturally generated in sucking up and distributing the oil by the gear pumps and this obstructs normal oil distribution. In this respect, it has been required to separate air from the oil bubbles and to exhaust the separated air to the outside while recovering the remaining oil. In order to achieve this object, the known oil gear pumps have been generally provided with individual air separators.
However in many cases, the known air separator has not been installed inside the gear pump, but installed at the outside of the gear pump because of structural limit of a main body of the gear pump.
For example, the known oil distribution gear pump generally has a float provided therein and a conventional air separator provided at the outside thereof. Thanking for such a construction, the float gradually rises as the inner space of the gear pump is gradually filled with the oil. When the float rises to reach a predetermined level, this float opens a bubble exhaust port and, as a result, the oil bubbles pass through the opened bubble exhaust port and are introduced into the air separator which is provided at the outside of the gear pump and where the air is separated from the oil bubbles. After separation, the air is exhausted to the outside, i.e., the atmosphere, through an air exhaust port but the remaining oil is recovered by an oil distribution chamber of the gear pump in order to be distributed therefrom.
However, this known gear pump must occupy considerable part of the inner space of the oil distributor due to the air separator provided at the outside of the gear pump in the oil distributor. In this regard, this type of gear pump has a disadvantage in that it resists to the recent trend of compactness and lightness of the oil distributors. Furthermore, it has been noted that there is difficulty in assembling and disassembling the gear pump due to the outside air separator and, therefore, this known gear pump has an additional disadvantage in that much labor must be consumed in manufacture and maintenance thereof.
In recent, a Japanese patent has disclosed an improved known gear pump technology to somewhat solve the above disadvantages. In this known Japanese technology, the air separator is equipped inside the gear pump and, in this respect, the recent trend of compactness and lightness of oil distributor can be somewhat achieved and the assembling and disassembling of the gear pump are relatively simplified and do not require much labor as opposed to the known gear pump having the outside air separator.
However, this type of pump necessarily requires to not only divide its inner space into several chambers, but also be provided with a linear ejection pipe which is adapted to strongly eject the oil bubbles. This linear ejection pipe has a uniform inner diameter throughout its length. Hence, much labor as well as many manufacturing steps must be necessary in manufacture of this type of gear pump, thereby causing manufacturing cost to be remarkably increased.
Accordingly, it has been required to provide an improved gear pump with an integrated air separator which can be manufactured through a relatively simplified process and, as a result, reduce manufacturing cost.
In an effort to achieve this object, there has been proposed an improved gear pump having an integrated air separator such as disclosed in Korean Patent Application No. 91-15775 applied by the present applicant.
This Korean patent has disclosed a gear pump of which inner space is divided into two chambers by an integral partition. This partition also has a bubble ejection pipe which is mounted on an upper part of this partition in such a manner that this pipe penetrates the upper part of the partition and maintains its position by employing screwed type mounting. In this regard, an inlet port of the bubble ejection pipe opens to the inner space of an oil distribution chamber of the pump, while an ejection port thereof opens to an oil recirculation chamber of the pump. In addition, a float is provided in an appropriate portion of the inner space of the oil recirculation chamber separated from the oil distribution chamber. In order to allow the air separated from the oil to be exhausted to the outside of the gear pump, i.e., the atmosphere, a main body of the gear pump is provided with an air exhaust port above the float. An oil recovering conduit is provided under the float so as to return the remaining oil to the oil distribution chamber. Here, the bubble ejection pipe has varied inner diameters such that input and ejection ends of the pipe have smaller inner diameters, respectively, while the center part of the pipe has an enlarged inner diameter.
Thanking for such a construction, when the oil gradually fills the inner space of the oil distribution chamber of the gear pump, the oil bubbles floating on the surface of the oil filling the chamber rise to a predetermined level. The oil bubbles are, thereafter, introduced into the bubble ejection pipe and in turn ejected from the ejection port of the bubble ejection pipe to the oil recirculation chamber including the float. At this time, the oil bubbles are pressurized when they pass through the ejection pipe due to the varied inner diameters of the pipe and ejected from the ejection port of the pipe at a considerable pressure. These bubbles ejected from the bubble ejection pipe strongly strike against the inner wall of the oil recirculation chamber and burst so as to separate the air from the oil bubbles. The separated air is, thereafter, exhausted to the outside of the gear pump through the air exhaust port. The remaining oil gradually fills the inner space of the oil recirculation chamber until the float rises to the predetermined level at which the float opens the oil recovering conduit. When the float opens the oil recovering conduit, the remaining oil passes through the opened oil recovering conduit in order to be recovered by the oil distribution chamber and in turn distributed therefrom.
This type of known gear pump, while somewhat simplifying its manufacturing process due to the integrated air separator and, as a result, reducing manufacturing cost, nevertheless has the bubble ejection pipe which penetrates the partition and is mounted thereon by employing the screwed type mounting. In this regard, this known gear pump has a disadvantage in that it still requires burdensome screw type mounting of the bubble ejection pipe and, furthermore, causes pure oil as well as the oil bubbles to be introduced into the bubble ejection pipe due to its construction. In addition, in this known gear pump, an eccentric gear assembly is rotatably supported on the pump main body using only a rotating shaft with no additional supporting members. In this respect, the oil distribution amount of this gear pump is deficient to satisfy a desired level.